Tuning magnetic interactions in ferromagnetic-metal nanoparticle systems

Abstract

We have experimentally studied the structure and magnetic interaction in Ni nanoparticle systems embedded in polymer matrices. The shrinkage of the matrices due to thermal decomposition leads to a decrease in the spacing among the particles, which maintain a fixed diameter of several nanometers. This is accompanied by a significant shift of electron magnetic-resonance signals. Based on the theoretical calculation, the shift is traced back to an enhancement of the magnetic dipolar interaction due to the diminution in the interparticle spacing, suggesting that we have succeeded in tuning the magnetic interaction in the nanoparticle systems.